I'd continue to use IPCop, if you don't want to get your hands dirty. I've herd a lot of good things about http://m0n0.ch/wall/ but then again I've never tested it.
What did you use IPCop for? Proxying, DNScache and firewalling? How many clients? What speed/type internet connection do you have.
I recently moved back to smoothwall from ipcop, I found that the new smoothwall has some awesome features compared to ipcop, like realtime bandwidth monitoring and a very good QOS interface, but the IDS service is f***** rooted, I think I don't have enough memory to start it.
Also the proxy services on smoothwall kicks some ass. the rules you can have for internal, outgoing & incoming are really nice, I had a mod on IPCOP that did that would help prevent applications from calling home.